- Fluoro-functionalized polymeric N-heterocyclic carbene-zinc complexes: Efficient catalyst for formylation and methylation of amines with CO2 as a C1-building block
-
A fluoro-functionalized polymeric N-heterocyclic carbene (NHC)-Zn complex (F-PNHC-Zn) was designed and synthesized by taking fluorous imidazolium salts as precursors through a two-step alkylation. The resultant F-PNHC-Zn was applied in catalyzing the formylation and methylation of amines using CO2 as a C1 building block in the presence of organosilane, which showed much higher activity than the corresponding non-fluorous PNHC-Zn under identical conditions. N-Methylanilines with both electron-withdrawing and electron-donating groups all could be converted to the corresponding formamides and methylamines in >90% conversion. Quantitative conversion of N-methylaniline was obtained even under very low CO2 pressure (0.05 MPa diluted by N2). Moreover, F-PNHC-Zn was highly stable and easily recyclable for these reactions. This journal is
- Yang, Zhen-Zhen,Yu, Bo,Zhang, Hongye,Zhao, Yanfei,Ji, Guipeng,Liu, Zhimin
-
-
Read Online
- Isolable CO2 Adducts of Polarized Alkenes: High Thermal Stability and Catalytic Activity for CO2 Chemical Transformation
-
Various CO2 adducts of tetra-hydropyrimidin-2-ylidene (THPE) derived from the commercially available 1, 5-diazabicyclo[4.3.0]non-5-ene (DBN) were firstly synthesized. X-ray single crystal analysis revealed the bent geometry of the binding CO2 having an O?C?O angle of 127.50～129.51° for THPE?CO2 adducts. In situ FTIR experiments demonstrated that THPE?CO2 adducts had unprecedented thermal stability in DMSO, even at 100 °C without decomposition. It was found that the THPE?CO2 adducts were highly active in catalyzing the carboxylative cyclization of CO2 with propargylic alcohols under mild conditions, significantly higher than the previously reported organocatalysts. Various internal and terminal functionalized propargylic alcohols were tolerated in these processes to afford the corresponding α-alkylidene cyclic carbonates in moderate to good yields with complete (Z)-stereoselectivity. Isotope labeling, in combination with in-situ FTIR and stoichiometric experiments, reveal that the catalytic reaction tends to proceed via the THPE?CO2-mediated basic ionic pair mechanism. (Figure presented.).
- Zhou, Hui,Zhang, Rui,Lu, Xiao-Bing
-
-
Read Online
- Phenonium ions from the addition of phenyl cations to alkenes. Photochemical synthesis of (rearranged) aminoalkylanilines from haloanilines in the presence of alkenes and amines
-
β-Aminoalkylanilines are smoothly obtained by irradiation of 4-chloro- and 4-fluoroanilines (as well as the N,N-dimethyl derivatives) in the presence of alkenes (1-hexene, cyclohexene) and amines (butylamine, piperidine) in polar, protic solvents such as trifluoroethanol (yield 40-75%). The reaction involves photoheterolysis of the haloaniline, addition of the resulting phenyl cation to the alkene and trapping of the phenonium cation by amine. A fraction (up to ca. 20%) of aminoalkylanilines resulting from Wagner-Meerwein rearrangement of the phenonium cation is obtained in some cases. Reduction and direct trapping of the phenyl cation by the amine compete with the above three-component synthesis in a less stabilizing solvent such as acetonitrile, but not in CF3-CH2OH.
- Guizzardi, Benedetta,Mella, Mariella,Fagnoni, Maurizio,Albini, Angelo
-
-
Read Online
- Photoinduced, ionic Meerwein arylation of olefins
-
Irradiation of 4-chloroaniline or of its N,N-dimethyl derivative in polar solvents generates the corresponding triplet phenyl cations. These are trapped by alkenes yielding arylated products in medium to good yields. B3LYP calculations show that the triplet cation slides with negligible activation energy to a bonded adduct with ethylene, whereas it forms only a marginally stabilized CT complex with water (chosen as a representative σ nucleophile). The structure of the final products depends on the preferred path from the adduct cation with the alkene. In the case of aryl olefins, this deprotonates to stilbene derivatives, while, from 2,3-dimethyl-2-butene and allytrimethylsilane, allylanilines are obtained by elimination of an electrofugal group in γ. In the case of mono- and disubstituted alkenes the cation adds chloride rather than eliminating and β-chloroalkylanilines are obtained. The regio- and sterochemistry of the addition across the alkene are best understood with a phenonium ion structure for the adduct. The nucleophile entering in fi can be varied under conditions in which the adduct cation is trapped more efficiently than the starting phenyl cation. Thus, β-methoxyalkylanilines are formed when the irradiation is carried out in methanol. β-Iodoalkylanilines are obtained in acetonitrile containing iodide and unsubstituted alkylanilines in the presence of sodium borohydride. A case of intramolecular nucleophilic trapping is found with 4-pentenoic acid. The reaction is a wide-scope ionic analogue of the radicalic Meerwin arylation of olefins.
- Mella,Coppo,Guizzardi,Fagnoni,Freccero,Albini
-
-
Read Online
- Ionization of Porous Hypercrosslinked Polymers for Catalyzing Room-Temperature CO2 Reduction via Formamides Synthesis
-
Porous materials with heterogeneous nature occupy a pivotal position in the chemical industry. This work described a facile pre- and post-synthetic approach to modify porous hypercrosslinked polymer with quaternary ammonium bromide, rendering it as efficient catalyst for CO2 conversion. The as-prepared porous ionic polymer (PiP@QA) displayed an improved specific surface area of 301 m2·g?1 with hierarchically porous structure, good selective adsorption of CO2, as well as high ion density. Accordingly, PiP@QA catalyst exhibited excellent catalytic performances for the solvent-free synthesis of various formamides from CO2, amines and phenylsilane under 35?°C and 0.5?MPa. We speculated that the superior catalytic efficiency and broad substrate scope of this catalyst could be resulted from the synergistic effect of flexible ionic sites with unique nanoporous channel that might increase the collision probability of reactants and active sites as well as enhance the diffusion of reactants and products during the reaction process. With the good reusability, PiP@QA was also available for the efficient conversion of simulated flue gas (15% CO2 in N2, v/v) into target formamides with quantitative selectivity at room temperature, which further highlighted its industrial application potential in chemical recycling the real-word CO2 to valuable products. Graphic Abstract: [Figure not available: see fulltext.].
- Ren, Qinggang,Chen, Yaju,Qiu, Yongjian,Tao, Leiming,Ji, Hongbing
-
-
Read Online
- Interaction of retinoic acid radical cation with lysozyme and antioxidants: Laser flash photolysis study in microemulsion
-
All-trans retinoic acid (ATRA) plays essential roles in the normal biological processes and the treatment of cancer and skin diseases. Considering its photosensitive property, many studies have been focused on the photochemistry of ATRA. In this study, we investigated the transient phenomena in the laser flash photolysis (LFP) of ATRA in microemulsion to further understand the photochemistry of ATRA. Results show that 355 nm LFP of ATRA in both acidic and alkaline conditions leads to the generation of retinoic acid cation radicals (ATRA?+) via biphotonic processes. The employment of microemulsion system allows us to investigate the reaction of hydrophobic ATRA?+ with molecules of different polarity. Therefore, we studied the reaction activity of ATRA?+ to many hydrophobic and hydrophilic molecules. Results show that ATRA?+ can efficiently interact with lysozyme, tyrosine, tryptophan and many antioxidants, such as curcumin (Cur), vitamin C (VC) and gallic acid (GA). The apparent rate constants of these reactions were measured and compared. These findings suggest that ATRA?+ is a reactive transient product which may pose damage to lysozyme, and antioxidants, such as Cur, VC and GA, may inactivate ATRA?+ by efficient quenching reactions. 355 nm laser flash photolysis of all-trans retinoic acid (ATRA) in microemulsion leads to the formation of retinoic acid cation radicals (ATRA?+) via biphotonic processes. Deprotonated form of ATRA is more favorable for the formation of ATRA?+. ATRA?+ is proved to be reactive to lysozyme, tyrosine and tryptophan which is suggestive of its destructive effect on proteins. Meanwhile, some antioxidants, such as curcumin, gallic acid and vitamin C, can efficiently interact with ATRA?+, which indicates that it may competitively protect proteins from the attack of ATRA?+ by inactivating free radical.
- Li, Kun,Wang, Mei,Wang, Ting,Sun, Dongmei,Zhu, Rongrong,Sun, Xiaoyu,Wu, Xianzheng,Wang, Shi-Long
-
-
Read Online
- Selective N-Methylation of N-Methylaniline with CO2 and H2 over TiO2-Supported PdZn Catalyst
-
A series of Pd-ZnO/TiO2, Pd/TiO2, and Pd/ZnO catalysts were synthesized and investigated for N-methylation of N-methylaniline (MA) to N,N-dimethylaniline (DMA) with CO2 and H2. A high performance was observed with a Pd-ZnO/TiO2 catalyst, with 99.9% DMA selectivity at 94% MA conversion. By contrast, both Pd/TiO2 and Pd/ZnO were less active and/or selective. The catalytic performance of Pd-ZnO/TiO2 largely depended on reduction temperature and ZnO loading. The rates for MA conversion (rateMA) and DMA production (rateDMA) increased linearly with the amount of PdZn alloy formed. The reaction was likely to take place via intermediates of N-methylformanilide (MFA) and formate. Formate was produced through the reduction of CO2 with H2 as confirmed by in situ diffuse reflectance Fourier transform infrared spectroscopy and then added to MA producing MFA, and finally, MFA was subsequently adsorbed and hydrogenated to DMA. All these steps were promoted by the PdZn alloy. The hydrogenation of MFA to DMA was much faster than the N-methylation of MA to MFA; DMA was stable, so the selectivity to DMA was almost 100% over the Pd-ZnO/TiO2 catalyst.
- Arai, Masahiko,Cheng, Haiyang,Lin, Weiwei,Wu, Qifan,Zhang, Chao,Zhao, Fengyu
-
-
Read Online
- Capillary-Bound Dense Micelle Brush Supports for Continuous Flow Catalysis
-
Flow reactors are appealing alternatives to conventional batch reactors for heterogeneous catalysis. However, it remains a key challenge to firmly immobilize the catalysts in a facile and flexible manner and to simultaneously maintain a high catalytic efficiency and throughput. Herein, we introduce a dense cylindrical micelle brush support in glass capillary flow reactors through a living crystallization-driven self-assembly process initiated by pre-immobilized short micelle seeds. The active hairy corona of these micellar brushes allows the flexible decoration of a diverse array of nanocatalysts, either through a direct capture process or an in situ growth method. The resulting flow reactors reveal excellent catalytic efficiency for a broad range of frequently utilized transformations, including organic reductions, Suzuki couplings, photolytic degradations, and multistep cascade reactions, and the system was both recyclable and durable. Significantly, this approach is readily applicable to long capillaries, which enables the construction of flow reactors with remarkably higher throughput.
- Cai, Jiandong,Cui, Yan,Lin, Geyu,Liu, Qiuwen,Manners, Ian,Qiu, Huibin,Sun, Yan
-
-
Read Online
- Absolute Estimates of PdII(n2-Arene) C-H Acidity
-
Thermodynamic acidity is one of the most widely used quantities for characterizing proton transfer reactions. Measurement of these values for catalytically relevant species can be challenging, often requiring direct observation of equilibria. The C-H bonds of aromatic substrates are proposed to become substantially polarized during electrophilic activation, but quantifying the absolute acidity of the intermediate M(n 2-arene) complexes is highly challenging. Using a system that intercepts nascent protons at electrophilic PdII arene complexes, a combined experimental and computational study has demonstrated these C-H bonds to be far more acidic (pKaCH3CN = 3-6) than many "nonbasic" substrates and additives that are present in electrophilic C-H activation catalysis, and the catalytic roles of these species may need to be reassessed.
- Christman, William E.,Morrow, Travis J.,Arulsamy, Navamoney,Hulley, Elliott B.
-
-
Read Online
- On the mechanism of the N,N-dimethyl amination of Grignard reagents: A kinetic study
-
A direct kinetic study is reported for the electrophilic amination of substituted phenylmagnesium bromides with N,N-dimethyl O-(mesitylenesulfonyl) hydroxylamine in THF. Rate data, Hammett relationship, and activation entropy are consistent with a SN2 displacement involving the attack of carbanions to sp3N in the amination reagent (AR). Copyright
- Erdik, Ender,Uelhue, Selma Ates
-
-
Read Online
- Smooth synthesis of aryl- and alkylanilines by photoheterolysis of haloanilines in the presence of aromatics and alkenes
-
Irradiation of 4-chloro-N,N-dimethylaniline in acetonitrile in the presence of benzene and of various alkenes leads to heterolytic dehalogenation and trapping of the cation. 4-(Dimethylamino)biphenyl is formed in the first case, while with alkenes β-chloroalkylanilines, stilbenes, or allylanilines are obtained depending on the alkene structure. 4-Fluoroaniline is similarly dehalogenated.
- Fagnoni, Maurizio,Mella, Mariella,Albini, Angelo
-
-
Read Online
- Solvent effects on nucleophilic substitution reactions. III. The effect of adding an inert salt on the structure of the SN2 transition state
-
The nitrogen and secondary α-hydrogen-deuterium kinetic isotope effects found for the SN2 reaction between thiophenoxide ion and benzyldimethylphenylammonium ion at different ionic strengths in DMF at 0°C indicate that the structure of the transition state changes markedly with the ionic strength of the reaction mixture. In fact, a more reactant-like, more ionic, transition state is found at the higher ionic strength. This presumably occurs because a more ionic transition state is more stable in the more ionic solvent.
- Pham,Westaway
-
-
Read Online
- A novel access to 3-aryl-2-norbornyl cation
-
A novel access to a 2-norbornyl cation under mild, non acidic conditions is found in the addition of photochemically generated 4-dimethylaminophenyl cation to 2-norbornene. Deprotonation to nortricyclene or nucleophile addition ensue depending on the solvent characteristics.
- Mella, Mariella,Esposti, Silvia,Fagnoni, Maurizio,Albini, Angelo
-
-
Read Online
- Mechanism of Boron-Catalyzed N-Alkylation of Amines with Carboxylic Acids
-
Mechanistic study has been carried out on the B(C6F5)3-catalyzed amine alkylation with carboxylic acid. The reaction includes acid-amine condensation and amide reduction steps. In condensation step, the catalyst-free mechanism is found to be more favorable than the B(C6F5)3-catalyzed mechanism, because the automatic formation of the stable B(C6F5)3-amine complex deactivates the catalyst in the latter case. Meanwhile, the catalyst-free condensation is constituted by nucleophilic attack and the indirect H2O-elimination (with acid acting as proton shuttle) steps. After that, the amide reduction undergoes a Lewis acid (B(C6F5)3)-catalyzed mechanism rather than a Br?nsted acid (B(C6F5)3-coordinated HCOOH)-catalyzed one. The B(C6F5)3)-catalyzed reduction includes twice silyl-hydride transfer steps, while the first silyl transfer is the rate-determining step of the overall alkylation catalytic cycle. The above condensation-reduction mechanism is supported by control experiments (on both temperature and substrates). Meanwhile, the predicted chemoselectivity is consistent with the predominant formation of the alkylation product (over disilyl acetal product).
- Zhang, Qi,Fu, Ming-Chen,Yu, Hai-Zhu,Fu, Yao
-
-
Read Online
- Efficient degradation of azo dyes using Ag and Au nanoparticles stabilized on graphene oxide functionalized with PAMAM dendrimers
-
Herein, we report the stabilization of silver and gold nanoparticles (Ag/Au NPs) on graphene oxide (GO) functionalized with PAMAM dendrimers. The grafting of the PAMAM dendrimers on GO has been investigated using TGA and Raman spectral studies and the stabilization of the Ag/Au NPs on the dendritic structures has been confirmed using XRD, UV-Vis and FT-IR spectra, SEM and TEM studies. The catalytic activity of the prepared nanocatalysts towards the degradation of organic azo dyes, namely methyl orange and congo red, has been tested. The prepared nanocatalysts were found to exhibit excellent catalytic activity towards the complete degradation of both methyl orange and congo red within only a few seconds.
- Rajesh, Rajendiran,Kumar, S. Senthil,Venkatesan, Rengarajan
-
-
Read Online
- α-Methylation of 2-Arylacetonitrile by a Trimethylamine-Borane/CO2 System
-
A highly selective monomethylation of 2-arylacetonitrile using CO2 is described. The utilization of trimethylamine-borane facilitates the six-electron reduction of CO2. This reaction is the first selective six-electron reductive functionalization of CO2 faciliated by C(sp3)-H bonds. A variety of 2-arylpropionitrile was obtained in good yields. The reaction could also be applied at the gram scale.
- Zhang, Xiaowei,Wang, Sheng,Xi, Chanjuan
-
-
Read Online
- Visible-Light-Induced C(sp2)-C(sp3) Cross-Dehydrogenative-Coupling Reaction of N-Heterocycles with N-Alkyl- N-methylanilines under Mild Conditions
-
Disclosed herein is a cross-dehydrogenative-coupling reaction of N-heterocycles including 1,2,4-triazine-3,5(2H, 4H)-diones and quinoxaline-2(1H)-ones with N-methylanilines to form C(sp2)-C(sp3) under visible-light illumination and ambient air at room temperature. In this process, easily available Ru(bpy)3Cl2·6H2O serves as the catalyst, and air acts as the green oxidant. This method features high atom economy, environmental friendliness, and convenient operation and provides an efficient and practical access to aminomethyl-substituted N-heterocycles with extensive functional group compatibility in 40-86% yields.
- Zhang, Hong-Yu,Chen, Jianjun,Lu, Cong-Cong,Han, Ya-Ping,Zhang, Yuecheng,Zhao, Jiquan
-
-
Read Online
- Ligand-protected Au4Ru2and Au5Ru2nanoclusters: Distinct structures and implications for site-cooperation catalysis
-
We report two ligand-protected Au4Ru2 and Au5Ru2 nanoclusters with distinct atomic-packing modes and electronic structures, both of which act as ideal model catalysts for identifying the catalytically active sites of catalysts on the nanoclusters. Au5Ru2 exhibits superior catalytic performances to Au4Ru2 for N-methylation of N-methylaniline to N-methylformanili, which is likely due to the site-cooperation catalysis of Au5Ru2. This journal is
- Sun, Yongnan,Yang, Dan,Zhang, Yuying,Hu, Weigang,Cheng, Xinglian,Liu, Xu,Chen, Mingyang,Zhu, Yan
-
-
Read Online
- REVERSIBLE PROTON TRANSFER IN THE 2,3,5,6-TETRACHLOROPHENOL-N,N-DIMETHYLANILINE HYDROGEN-BONDED COMPLEX STUDIED BY LOW-TEMPERATURE 1H NMR SPECTROSCOPY
-
Low temperature 1H NMR studies of the bridging OHN signal in the hydrogen-bonded complex formed between 2,3,5,6-tetrachlorophenol and N,N-dimethylaniline in C2H5Cl solution have shown that separate signals for the molecular and ion-pair forms of the complex can be observed below -135 deg C (138 K).Analyses of the observed lineshapes have yielded values for the thermodynamic quantities ΔH0, ΔS0 as well as for the activation quantities ΔH, ΔS.
- Ilczyszyn, Marek,Ratajczak, Henryk,Ladd, John A.
-
-
Read Online
- Zn(ii)@TFP-DAQ COF: An efficient mesoporous catalyst for the synthesis of: N -methylated amine and carbamate through chemical fixation of CO2
-
Selective N-methylation and carbamate formation reactions were demonstrated via the chemical incorporation of CO2 using a Zn-loaded TFP-DAQ COF (covalent organic framework) as an active catalyst under mild reaction conditions. The selective N-methylation and N-formylation reactions were performed by simply varying the type of solvent. The Zn(ii)@TFP-DAQ COF catalyst was characterized via different characterization techniques such as PXRD, FTIR, UV-vis, N2 adsorption-desorption studies, FESEM and TEM. The catalyst material showed pores in the mesoporous region with a high surface area of 1117.375 m2 g-1. The as-synthesized material was applied as a cheap catalyst for the N-methylation of secondary amines and in carbamate formation reactions with high yields of the desired products up to 98.5% and 97%, respectively, with >99% selectivity. The catalyst was found to be completely heterogeneous and reusable for multiple reaction cycles.
- Sarkar, Priyanka,Chowdhury, Arpita Hazra,Riyajuddin, Sk.,Biswas, Surajit,Ghosh, Kaushik,Islam, Sk. Manirul
-
-
Read Online
- C–N cross-coupling on supported copper catalysts: The effect of the support, oxidation state, base and solvent
-
A series of supported copper catalysts at two different loadings (1 and 2?wt%) have been prepared by deposition precipitation on various supports including TiO2, ZnO, Al2O3 and active carbon and submitted or not to reductive treatments to favor the increase in population of Cu(I). The samples have been characterized by textural measurements, electron microscopy and spectroscopic techniques including EPR and XPS, concluding the presence of dispersed copper oxides on the support with small particle size and contrasting prevalence of Cu(II) or Cu(I). The catalytic activity of all these catalysts for the C–N coupling of aniline and bromobenzene has been evaluated. A strong influence of the support, copper oxidation state, solvent, nature of the base was observed, the optimal conditions being the use of ZnO or TiO2 as supports and toluene/dioxane as solvent and EtOK as base. t-C5H11OK as base in either THF or toluene give rise to the formation of t-C5H11 phenyl ether in some extent. The catalyst undergoes deactivation during the reaction, but about 88% of the activity of the fresh sample could be regained by dioxane washings before reuse. XPS indicates that the most likely origin of catalyst deactivation is adsorption on the copper catalyst surface of KBr and inorganic salts formed as byproducts during the reaction.
- Tirsoaga, Alina,Cojocaru, Bogdan,Teodorescu, Cristian,Vasiliu, Florin,Grecu, Maria Nicoleta,Ghica, Daniela,Parvulescu, Vasile I.,Garcia, Hermenegildo
-
-
Read Online
- Unexpected Macrocyclic Multinuclear Zinc and Nickel Complexes that Function as Multitasking Catalysts for CO2 Fixations
-
Unique self-assembled macrocyclic multinuclear ZnII and NiII complexes with binaphthyl-bipyridyl ligands (L) were synthesized. X-ray analysis revealed that these complexes consisted of an outer ring (Zn3L3 or Ni3L3) and an inner core (Zn2 or Ni). In the ZnII complex, the inner Zn2 part rotated rapidly inside the outer ring in solution on an NMR timescale. These complexes exhibited dual catalytic activities for CO2 fixations: synthesis of cyclic carbonates from epoxides and CO2 and temperature-switched N-formylation/N-methylation of amines with CO2 and hydrosilane.
- Takaishi, Kazuto,Nath, Bikash Dev,Yamada, Yuya,Kosugi, Hiroyasu,Ema, Tadashi
-
-
Read Online
- N-Mannich Bases of Aromatic Heterocyclic Amides: Synthesis via Copper-Catalyzed Aerobic Cross-Dehydrogenative Coupling under Ambient Conditions
-
An efficient and facile method to synthesize N-Mannich bases has been developed using an inexpensive copper(I) bromide/air catalyst system at ambient temperature. A cross-dehydrogenative coupling of N,N-dimethylarylamines occurs efficiently with aromatic heterocyclic amides (oxindoles, isatins), cyclic amides (lactams), simple amides (benzamide), as well as imides (succinimide, phthalimide) to furnish the corresponding amidated/imidated derivatives in good to excellent yields. Preliminary mechanistic and isotope-labeling studies suggest the reaction follows a radical pathway and involves an iminium ion intermediate.
- Singh, Shailendra K.,Chandna, Nisha,Jain, Nidhi
-
-
Read Online
- T-BuC5H43Nd: A triscyclopentadienyl rare earth compound as non-classical isoprene polymerization pre-catalyst
-
eptic tris(cyclopentadienyl) Cp′ 3Nd (Cp′ = C 5H4t-Bu) complex has been unprecedentedly considered as potential pre-catalyst for isoprene polymerization. The X-ray structural analysis establishes a monomeric non-solvated nature for this compound. Upon activation with appropriate borate/aluminium co-catalyst combinations, Cp0 3Nd affords in good yields polyisoprene more than 95% cis-regular.
- Rodrigues, Ines,Xue, Tan Yong,Roussel, Pascal,Visseaux, Marc
-
-
Read Online
- Kinetics of One-Electron Transfer Reactions Involving ClO2 and NO2
-
Rate constants for the one-electron oxidation of ClO2(1-) and NO2(1-) by several organic and inorganic free radicals have been measured along with rate constants for several reactions of ClO2, NO2 and BrO2.The kinetics of the reactions of ClO2 and NO2 are consistent with simple electron-transfer theory, except for the reaction of NO2 with SO3(2-), which appears to be oxygen atom transfer.Equilibrium constants have been determined for the reactions of ClO2 with aniline at pH 6.9 and N,N-dimethylaniline at pH 9.6.This leads to one-electron redox potentials of 1.03 and 0.87 V for these aromatic amines, respectively, at the corresponding pH.
- Huie, Robert E.,Neta, P.
-
-
Read Online
- Energy and environmental applications of ultrasonically sulfur doped copper-nickel hydroxides with heterostructures
-
A series of sulfur doped copper-nickel hydroxides with heterojunctions were successfully fabricated on nickel foam by adjusting thiourea volume via a facile sonochemical pathway. The effect of volume of thiourea on the final morphology and chemical composition of the hybrids were also investigated by field-emission scanning electron microscopy, and X-ray photoelectron spectroscopy analyses. Furthermore, the electrochemical performance and catalytic activity of the as-obtained hybrids were also investigated. Among the tested electrode, the hybrid material fabricated using 6 ml of thiourea (TU-6) showed outstanding electrochemical properties comprising a high specific capacitance of about 2708 F g?1 at 5 A g?1. In addition, the TU-6 hybrid (catalyst) material displayed remarkable reductive degradation ability towards azo dyes viz., methyl orange (within 8 min) and congo red (within 20 min) in the presence of sodium borohydride (reducing agent) with fast kinetics and good reproducibility, respectively. The exceptional electrochemical performance and excellent catalytic activity of TU-6 hybrid electrode may be attributed to the formation of catalytically active sulfur doped copper-nickel hydroxides (CuS/Ni3S2/NiOOH) three-interface synergistic effect, and unique porous micro-rosette-like texture which increased the diffusion rate and adsorption capacity. The adopted strategy is a simple and generic way for material fabrication to solve the energy and environmental problems.
- Karthik, Namachivayam,Edison, Thomas Nesakumar Jebakumar Immanuel,Atchudan, Raji,Sethuraman, Mathur Gopalakrishnan
-
-
Read Online
- N, N -Dimethylation of nitrobenzenes with CO2 and water by electrocatalysis
-
We have proposed a strategy for the synthesis of N,N-dimethylanilines from nitrobenzene and its derivatives, CO2, and water via an electrochemical reaction under ambient conditions. H+ generated from H2O was used as the hydrogen source. Pd/Co-N/carbon, in which the Pd nanoparticles were supported on Co-N/carbon, was designed and used as the electrocatalyst. It was found that the electrocatalyst was very efficient for the reaction in MeCN solution with 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim]Tf2N) as the supporting electrolyte and 1-amino-methylphosphonic acid (AMPA) as the thermal co-catalyst. A series of control experiments showed that Pd/Co-N/carbon and AMPA cooperated very well in accelerating the reaction. This synthetic route has some obvious advantages, such as using CO2 and water as the reactants, ambient reaction conditions, and high yields of the desired products. This opens up a way to synthesize chemicals by the combination of an electrocatalyst and a thermal catalyst with organic compounds, CO2, and water as the reactants.
- Sun, Xiaofu,Zhu, Qinggong,Hu, Jiayin,Kang, Xinchen,Ma, Jun,Liu, Huizhen,Han, Buxing
-
-
Read Online
- One-Electron Redox Reactions Involving Sulfite Ions and Aromatic Amines
-
The one-electron oxidation of aromatic amines by the SO3- radical and of the sulfite and bisulfite ions by aromatic amine radical cations has been investigated. p-Phenylenediamine (PDA) and N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) were oxidized by SO3- with rate constant of 5.0 x 1E7 and 5.2 x 1E8 M-1 s-1, respectively, in basic solutions.Protonations of the amine reduced the rates considerably (k = 4.2 x 1E6 M-1 s-1 for PDA at pH 5.25; k = 8.2 x 1E6 M-1 s-1 for TMPD at pH 4.5).Witn aniline and N,N-dimethylaniline (DMA), the reverse reaction was observed.DMA+ radical reacted with SO32- with k = 9.9 x 1E8 M-1 s-1 and with HSO3- k -1 s-1.Aniline radical cation also oxidized SO32- rapidly (k = 4 x 1E9 M-1 s-1) and HSO3- less rapidly (k = 4.8 x1E6 M-1 s-1).The aniline neutral radical reacted too slowly to be measured with either.A secondary product was observed in acid solution of TMPD with an absorption maximum at 455 nm.This was ascribed to a reaction between the SO3- and TMPD+ radicals.
- Neta, P.,Huie, Robert E.
-
-
Read Online
- Homolytic vs Heterolytic Paths in the Photochemistry of Haloanilines
-
The photochemistry of 4-haloanilines and 4-halo-N,N-dimethylanilines has been studied in apolar, polar aprotic, and protic solvents. Photophysical and flash photolysis experiments show that the reaction proceeds in any case from the triplet state. It is rather unreactive in apolar media, the highest value being Π = 0.05 for the iodoanilines in cyclohexane. Changing the solvent has little effect for iodoanilines and for the poorly reacting bromo analogue, while it leads to a variation of over 2 orders of magnitude in the quantum yield for the chloro and fluoro derivatives. The triplets have been characterized at the UB3LYP/6-31G(d) level of theory, evidencing a deformation and an elongation (except for C-F) of the C-X bond. Homolytic fragmentation is in every case endothermic, but calculations in acetonitrile solution show that heterolytic cleavage of C-Cl and C-Br is exothermic. Experimentally, the occurrence of heterolytic fragmentation has been monitored through selective trapping of the resulting phenyl cation by allyltrimethylsilane. Heterolytic dechlorination occurs efficiently in polar media (e.g., Π = 0.77 in MeCN), while debromination remains ineffective due to the short lifetime of the triplet. Heterolytic defluorination is efficient only in protic solvents (Π = 0.48 in MeOH), in accord with calculations showing that in the presence of an ancillary molecule of water fragmentation is exothermic due to the formation of the strong H-F bond. The energy profile for both homo- and heterolytic dissociation paths has been mapped along the reaction coordinates in the gas phase and in acetonitrile. The conditions determining the efficiency and mode of dehalogenation have been defined. This is significant for devising synthetic methods via photogenerated phenyl cations and for rationalizing the photodegradation of halogenated aromatic pollutants and the phototoxic effect of some fluorinated drugs.
- Freccero, Mauro,Fagnoni, Maurizio,Albini, Angelo
-
-
Read Online
- Highly efficient and simultaneous catalytic reduction of multiple dyes using recyclable RGO/Co dendritic nanocomposites as catalyst for wastewater treatment
-
Development of a low cost, highly efficient and easily retrievable catalyst with improved reusability is a major challenge in the area of advanced catalysts. In this study, we report a simple one-step approach for the fabrication of a reduced graphene oxide (RGO)/Co dendritic nanocomposite. The structure and morphology of the as synthesized material are thoroughly examined by XRD, Raman, FTIR, TEM, and SEM. The magnetic properties of the RGO/Co dendritic nanocomposite reveal that it exhibits ferromagnetic behavior at room temperature with high saturation magnetization. The catalytic activity of the RGO/Co dendritic nanocomposite was investigated for the reduction of different dyes namely, 4-nitrophenol, methylene blue, methyl orange and rhodamine B individually, and their mixture in the presence of a sufficient amount of NaBH4. RGO/Co dendritic nanocomposite exhibits excellent catalytic activity as compared to the bare Co dendritic structure. The catalyst could be easily separated by an external magnet and recycled magnetically with no major loss of catalytic activity upto five cycles. The high catalytic efficiency, low cost and easy recycle technique make RGO/Co dendritic nanocomposite a proficient catalyst for degradation of organic dyes.
- Sahoo, Prasanta Kumar,Thakur, Dinbandhu,Bahadur,Panigrahy, Bharati
-
p. 106723 - 106731
(2016)
-
Read Online
- Functional Hyper-Crosslinked Polypyrene for Reductive Decolorization of Industrial Dyes and Effective Mercury Removal from Aqueous Media
-
A rigid and valuable hyper-crosslinked polymer (HCP) has been synthesized from the polycyclic aromatic hydrocarbon pyrene: hyper-crosslinked polypyrene (HCPPy). HCPPy was prepared through a simple one-step Friedel-Crafts alkylation reaction that involves ZnBr2-catalyzed crosslinking in the presence of an external crosslinker, bromomethyl methyl ether (BME). Interestingly, the unreacted bromomethyl groups (?CH2Br) on the surface of HCPPy could be quantified, which later aided in modification as per our requirement. We aimed at modifying with disulfide-containing cystamine dihydrochloride (Cys-HCPPy). Cys-HCPPy exhibited an extended π-conjugated system with uniform (～1 μm diameter) morphology and high porosity (specific surface area: 445 m2 g?1). As a fundamental application, the Cys-HCPPy composite was used as a sorbent to remove Hg2+ ions from aqueous media. Thus, at pH 6, the adsorption capacity for mercury ions reached 1124.82 mg g?1 after 24 h. Furthermore, the immobilization of Ag nanoparticles on the surface of Cys-HCPPy (Ag@Cys-HCPPy) enhanced the catalytic properties, which allowed for the reductive decolorization of industrial dyes such as methylene blue, methyl orange, and Congo Red in the presence of NaBH4 as a reducing agent.
- Varyambath, Anuraj,Song, Wen L.,Kim, Il
-
-
Read Online
- Additive-free selective methylation of secondary amines with formic acid over a Pd/In2O3 catalyst
-
Formic acid is used as the sole carbon and hydrogen source in the methylation of aromatic and aliphatic amines to methylamines. The reaction proceeds via a formylation/transfer hydrogenation pathway over a solid Pd/In2O3 catalyst without the need for any additive.
- Benaissa, Idir,Cantat, Thibault,Genre, Caroline,Godou, Timothé,Pinault, Mathieu
-
-
- Green and chemo selective amine methylation using methanol by an organometallic ruthenium complex
-
Herein a green and convenient catalytic N-methylation of aniline and n-hexylamine using methanol as a dual methylation agent and solvent has been investigated. A new ruthenium carbonyl complex was synthesized and applied as a homogeneous catalyst in methylation reaction. The solid-state structure of the complex was determined by X-ray crystallographic analysis which indicate xantphos ligand bonded to ruthenium (II) as a tridentate pincer ligand by two P donor and one O atom. The catalytic system showed excellent conversion and selectivity toward N-methylaniline, and N,N-hexyldimethylamine at 140°C.
- Abbasi, Alireza,Dindar, Sara,Nemati Kharat, Ali
-
-
- Trialkylammonium salt degradation: Implications for methylation and cross-coupling
-
Trialkylammonium (most notably N,N,N-trimethylanilinium) salts are known to display dual reactivity through both the aryl group and the N-methyl groups. These salts have thus been widely applied in cross-coupling, aryl etherification, fluorine radiolabelling, phase-transfer catalysis, supramolecular recognition, polymer design, and (more recently) methylation. However, their application as electrophilic methylating reagents remains somewhat underexplored, and an understanding of their arylation versus methylation reactivities is lacking. This study presents a mechanistic degradation analysis of N,N,N-trimethylanilinium salts and highlights the implications for synthetic applications of this important class of salts. Kinetic degradation studies, in both solid and solution phases, have delivered insights into the physical and chemical parameters affecting anilinium salt stability. 1H NMR kinetic analysis of salt degradation has evidenced thermal degradation to methyl iodide and the parent aniline, consistent with a closed-shell SN2-centred degradative pathway, and methyl iodide being the key reactive species in applied methylation procedures. Furthermore, the effect of halide and non-nucleophilic counterions on salt degradation has been investigated, along with deuterium isotope and solvent effects. New mechanistic insights have enabled the investigation of the use of trimethylanilinium salts in O-methylation and in improved cross-coupling strategies. Finally, detailed computational studies have helped highlight limitations in the current state-of-the-art of solvation modelling of reaction in which the bulk medium undergoes experimentally observable changes over the reaction timecourse. This journal is
- Assante, Michele,Baillie, Sharon E.,Juba, Vanessa,Leach, Andrew G.,McKinney, David,Reid, Marc,Washington, Jack B.,Yan, Chunhui
-
p. 6949 - 6963
(2021/06/02)
-
- CO2-tuned highly selective reduction of formamides to the corresponding methylamines
-
We herein describe an efficient, CO2-tuned and highly selective C-O bond cleavage of N-methylated formanilides. With easy-to-handle and commercially available NaBH4 as the reductant, a variety of formanilides could be turned into the desired tertiary amines in moderate to excellent yields. The role of CO2 has been investigated in detail, and the mechanism is proposed on the basis of experiments.
- Chao, Jianbin,Guo, Zhiqiang,Pang, Tengfei,Wei, Xuehong,Xi, Chanjuan,Yan, Leilei
-
supporting information
p. 7534 - 7538
(2021/10/12)
-
- Alcohol promoted N -methylation of anilines with CO2/H2over a cobalt catalyst under mild conditions
-
N-Methylation of amines with CO2/H2 to N-methylamines over non-noble metal catalysts is very interesting but remains challenging. Herein, we present an alcohol (e.g., ethanol) promoted strategy for the N-methylation of anilines with CO2/H2 with high efficiency under mild conditions (e.g., 125 °C), which is achieved over a cobalt catalytic system composed of Co(OAc)2·4H2O, triphos and Sn(OTf)2. This catalytic system has a broad substrate scope and is tolerant toward a wide range of anilines and N-methyl anilines, and a series of N,N-dimethyl anilines were obtained in high yields. Mechanism investigation indicates that the alcohol solvent shifts the equilibrium of CO2 hydrogenation by forming an alkyl formate, which further reacts with the amine to produce N-formamide, and Sn(OTf)2 promotes the deoxygenative hydrogenation of N-formamides to afford N-methylamines. This is the first example of the N-methylation of amines with CO2/H2 over a cobalt catalytic system, which shows comparable performance to the reported Ru catalysts and may have promising applications.
- Han, Buxing,Ke, Zhengang,Li, Ruipeng,Liu, Zhimin,Tang, Minhao,Wang, Huan,Zeng, Wei,Zhao, Yanfei
-
p. 9147 - 9153
(2021/11/30)
-
- Simplified preparation of a graphene-co-shelled Ni/NiO@C nano-catalyst and its application in theN-dimethylation synthesis of amines under mild conditions
-
The development of Earth-abundant, reusable and non-toxic heterogeneous catalysts to be applied in the pharmaceutical industry for bio-active relevant compound synthesis remains an important goal of general chemical research.N-methylated compounds, as one of the most essential bioactive compounds, have been widely used in the fine and bulk chemical industries for the production of high-value chemicals. Herein, an environmentally friendly and simplified method for the preparation of graphene encapsulated Ni/NiO nanoalloy catalysts (Ni/NiO@C) was developed for the first time, for the highly selective synthesis ofN-methylated compounds using various functional amines and aldehydes under easy to handle, and industrially applicable conditions. A large number of primary and secondary amines (more than 70 examples) could be converted to the correspondingN,N-dimethylamines with the participation of different functional aldehydes, with an average yield of over 95%. A gram-scale synthesis also demonstrated a similar yield when compared with the benchmark test. In addition, it was further proved that the catalyst could easily be recycled because of its intrinsic magnetism and reused up to 10 times without losing its activity and selectivity. Also, for the first time, the tandem synthesis ofN,N-dimethylamine products in a one-pot process, using only a single earth-abundant metal catalyst, whose activity and selectivity were more than 99% and 94%, respectively, for all tested substrates, was developed. Overall, the advantages of this newly developed method include operational simplicity, high stability, easy recyclability, cost-effectiveness of the catalyst, and good functional group compatibility for the synthesis ofN-methylation products as well as the industrially applicable tandem synthesis process.
- Liu, Jianguo,Ma, Longlong,Song, Yanpei,Zhang, Mingyue,Zhuang, Xiuzheng
-
supporting information
p. 4604 - 4617
(2021/06/30)
-
- Efficient base-free hydrodehalogenation of organic halides catalyzed by a well-defined diphosphine-ruthenium(II) complex
-
A base-free, robust catalytic system based on the diphosphine-ruthenium(II) complex cation has been developed for the hydrodehalogenation of a wide range of aryl- and alkyl-chlorides/bromides (27 examples) with molecule hydrogen. Notably, the reaction proceeds at 120 °C with low catalyst loading (0.1 mol%) and exhibits a good tolerance toward functional groups, such as amido, carboxyl, sulfonyl, methoxyl, ester groups. All dehalogenation products are confirmed by GC, GC–MS and NMR spectroscopy. Moreover, a mechanism for the diphosphine-ruthenium(II) complex cation catalyzed dehalogenation process has been proposed. This hydrodehalogenation methodology shows a potential application for the organic transformation and degradation of organic halides.
- Gao, Pengxiang,Liu, Qingbin,Liu, Yahuan,Ma, Ning,Wang, Zheng,Zhao, Ziwei
-
-
- Method for realizing N-alkylation by using alcohols as carbon source under photocatalysis
-
The invention discloses a method for realizing N-alkylation by using alcohols as a carbon source under photocatalysis, and belongs to the technical field of catalytic synthesis. Alcohol, a substrate raw material and a catalyst are placed in a reaction device, ultraviolet and/or visible light irradiation is carried out in an inert atmosphere, after the irradiation is finished, solid-liquid separation is carried out to remove the catalyst, and an N-alkylation product can be obtained through extraction, distillation and purification, wherein the substrate raw material comprises any one of an amine compound, an aromatic nitro compound or an aromatic nitrile compound, the alcohol comprises any one or more of soluble primary alcohols, and the catalyst is metal oxide/titanium dioxide or metal sulfide/titanium dioxide. The method is simple and easy to operate, can be used for efficient photocatalysis one-pot multi-step hydrogenation N-alkylation reaction, and is mild in reaction condition, high in chemical selectivity of N-alkylamine, good in catalyst stability and easy to recycle.
- -
-
Paragraph 0048-0099
(2021/03/13)
-
- Additive-freeN-methylation of amines with methanol over supported iridium catalyst
-
An efficient and versatile zinc oxide-supported iridium (Ir/ZnO) catalyst was developed to catalyze the additive-freeN-methylation of amines with methanol. Mechanistic studies suggested that the high catalytic reactivity is rooted in the small sizes (1.4 nm) of Ir nanoparticles and the high ratio (93%) of oxidized iridium species (IrOx, Ir3+and Ir4+) on the catalyst. Moreover, the delicate cooperation between the IrOxand ZnO support also promoted its high reactivity. The selectivity of this catalyticN-methylation was controllable between dimethylation and monomethylation by carefully tuning the catalyst loading and reaction solvent. Specifically, neat methanol with high catalyst loading (2 mol% Ir) favored the formation ofN,N-dimethylated amine, while the mesitylene/methanol mixture with low catalyst loading (0.5 mol% Ir) was prone to producing mono-N-methylated amines. An environmentally benign continuous flow system with a recycled mode was also developed for the efficient production ofN-methylated amines. With optimal flow rates and amine concentrations, a variety ofN-methylamines were produced with good to excellent yields in this Ir/ZnO-based flow system, providing a starting point for the clean and efficient production ofN-methylamines with this cost-effective chemical process.
- Liu, Xiang,Loh, Teck-Peng,Qiang, Wenwen,Wang, Jing,Ye, Sen,Zhu, Longfei
-
p. 3364 - 3375
(2021/06/06)
-
- Preparation method of N-alkylated derivative of primary amine compound
-
The invention relates to a preparation method of an N-alkylated derivative of a primary amine compound. The method comprises the following steps: uniformly mixing a primary amine compound, an alcohol compound and a catalyst in a reactor, and heating to react for a period of time to generate an N-alkylated substituted tertiary amine compound; wherein the catalyst is a copper-cobalt bimetallic catalyst, and the carrier of the catalyst is Al2O3. According to the method, alcohol is adopted as an alkylating reagent and is low in price and easy to obtain, a byproduct is water, no pollution is caused to the environment, and the overall reaction atom economy is high; the catalyst is simple in preparation method, low in cost, high in reaction activity and good in structural stability; meanwhile, by using the copper-cobalt bimetallic catalyst, the use of strong base additives can be avoided, and the requirement on reaction equipment is low; and the reaction post-treatment is convenient, and the catalyst can be recycled and is environment-friendly.
- -
-
Paragraph 0021-0037
(2021/07/09)
-
- Metallocene compound containing indenoindole structure, preparation method and application thereof, and preparation method of alpha-olefin
-
The invention provides a metallocene compound containing an indenoindole structure, a preparation method and application thereof, and a preparation method of alpha-olefin. The metallocene compound containing the indenoindole structure provided by the invention has a structure as shown in a formula (A) or a formula (B), can be used as a catalyst for catalytic synthesis of alpha-olefin, and can be used for high-activity and high-selectivity synthesis of high-carbon-number alpha-olefin, and the main components in the product are 1-octene, 1-decene and 1-dodecene.
- -
-
Paragraph 0128; 0154-0157
(2021/06/09)
-
- Metal-Free Deoxygenation of Amine N-Oxides: Synthetic and Mechanistic Studies
-
We report herein an unprecedented combination of light and P(III)/P(V) redox cycling for the efficient deoxygenation of aromatic amine N-oxides. Moreover, we discovered that a large variety of aliphatic amine N-oxides can easily be deoxygenated by using only phenylsilane. These practically simple approaches proceed well under metal-free conditions, tolerate many functionalities and are highly chemoselective. Combined experimental and computational studies enabled a deep understanding of factors controlling the reactivity of both aromatic and aliphatic amine N-oxides.
- Lecroq, William,Schleinitz, Jules,Billoue, Mallaury,Perfetto, Anna,Gaumont, Annie-Claude,Lalevée, Jacques,Ciofini, Ilaria,Grimaud, Laurence,Lakhdar, Sami
-
p. 1237 - 1242
(2021/06/01)
-
- Cr-Catalyzed Direct ortho-Aminomethylation of Phenols
-
We developed a Cr-catalyzed strategy for the regioselective formation of Csp2–Csp3 bonds through the direct and efficient ortho-aminomethylation of N,N-dimethylanilines with phenols. The approach showed excellent site selectivity at the ortho-position of phenols and accommodated broad substrate scope and functional group compatibility for both N,N-dimethylanilines and phenols. Mechanistic studies revealed that the direct ortho-aminomethylation between N,N-dimethylanilines and phenols occurred via an ionic mechanism.
- Shi, Junbin,Wang, Yubin,Bu, Qingqing,Liu, Binyuan,Dai, Bin,Liu, Ning
-
p. 17567 - 17580
(2021/12/17)
-
- Metal-Free Photoredox-Catalyzed Hydrodefluorination of Fluoroarenes Utilizing Amide Solvent as Reductant
-
A metal-free photoredox-catalyzed hydrodefluorination of fluoroarenes was achieved by using N,N,N’,N’-tetramethyl-para-phenylenediamine (1) as a strong photoreduction catalyst. This reaction was applicable not only to electron-rich monofluoroarenes but also to polyfluoroarenes to afford non-fluorinated arenes. The experimental mechanistic studies indicated that the amide solvent NMP plays an important role for regeneration of the photocatalyst, enabling additive-free photoreduction catalysis.
- Toriumi, Naoyuki,Yamashita, Kazuya,Iwasawa, Nobuharu
-
supporting information
p. 12635 - 12641
(2021/08/03)
-
- Photocatalytic Water-Splitting Coupled with Alkanol Oxidation for Selective N-alkylation Reactions over Carbon Nitride
-
Photocatalytic water splitting technology (PWST) enables the direct use of water as appealing “liquid hydrogen source” for transfer hydrogenation reactions. Currently, the development of PWST-based transfer hydrogenations is still in an embryonic stage. Previous reports generally centered on the rational utilization of the in situ generated H-source (electrons) for hydrogenations, in which photogenerated holes were quenched by sacrificial reagents. Herein, the fully-utilization of the liquid H-source and holes during water splitting is presented for photo-reductive N-alkylation of nitro-aromatic compounds. In this integrate system, H-species in situ generated from water splitting were designed for nitroarenes reduction to produce amines, while alkanols were oxidized by holes for cascade alkylating of anilines as well as the generated secondary amines. More than 50 examples achieved with a broad range scope validate the universal applicability of this mild and sustainable coupling approach. The synthetic utility of this protocol was further demonstrated by the synthesis of existing pharmaceuticals via selective N-alkylation of amines. This strategy based on the sustainable water splitting technology highlights a significant and promising route for selective synthesis of valuable N-alkylated fine chemicals and pharmaceuticals from nitroarenes and amines with water and alkanols.
- Xu, Yangsen,Zhang, Zhaofei,Qiu, Chuntian,Chen, Shaoqin,Ling, Xiang,Su, Chenliang
-
p. 582 - 589
(2020/12/09)
-
- Reductive Alkylation of Azides and Nitroarenes with Alcohols: A Selective Route to Mono- And Dialkylated Amines
-
Herein, we demonstrated an efficient protocol for reductive alkylation of azides/nitro compounds via a borrowing hydrogen (BH) method. By following this protocol, selective mono- and dialkylated amines were obtained under mild and solvent-free conditions. A series of control experiments and deuterium-labeling experiments were performed to understand this catalytic process. Mechanistic studies suggested that the Ir(III)-H was the active intermediate in this reaction. KIE study revealed that the breaking of the C-H bond of alcohol might be the rate-limiting step. Notably, this solvent-free strategy disclosed a high TON of around 5600. Based on kinetic studies and control experiments, a metal-ligand cooperative mechanism was proposed.
- Borthakur, Ishani,Joshi, Abhisek,Kundu, Sabuj,Maji, Milan
-
-
- Heterogeneously Catalyzed Selective Decarbonylation of Aldehydes by CeO2-Supported Highly Dispersed Non-Electron-Rich Ni(0) Nanospecies
-
Aldehyde decarbonylation has been extensively investigated, primarily using noble-metal catalysts; however, nonprecious-base-metal-catalyzed aldehyde decarbonylation has been hardly reported. We have established an efficient selective aldehyde decarbonylation reaction with a broad substrate scope and functional group tolerance utilizing a heterogeneous Ni(0) nanospecies catalyst supported on CeO2. The high catalytic performance is attributable to the highly dispersed and non-electron-rich Ni(0) nanospecies, which possibly suppress a side reaction producing esters and adsorbed CO-derived inhibition of the catalytic turnover, according to detailed catalyst characterization and kinetic evaluation.
- Matsuyama, Takehiro,Yatabe, Takafumi,Yabe, Tomohiro,Yamaguchi, Kazuya
-
p. 13745 - 13751
(2021/11/17)
-
- Nickel-Catalyzed Amination of Aryl Chlorides with Amides
-
A nickel-catalyzed amination of aryl chlorides with diverse amides via C-N bond cleavage has been realized under mild conditions. A broad substrate scope with excellent functional group tolerance at a low catalyst loading makes the protocol powerful for synthesizing various aromatic amines. The aryl chlorides could selectively couple to the amino fragments rather than the carbonyl moieties of amides. Our protocol complements the conventional amination of aryl chlorides and expands the usage of inactive amides.
- Li, Jinpeng,Huang, Changyu,Wen, Daheng,Zheng, Qingshu,Tu, Bo,Tu, Tao
-
supporting information
p. 687 - 691
(2021/01/09)
-
- Mesoionic N-heterocyclic olefin catalysed reductive functionalization of CO2for consecutiveN-methylation of amines
-
A mesoionic N-heterocyclic olefin (mNHO) was introduced as a metal-free catalyst for the reductive functionalization of CO2leading to consecutive doubleN-methylation of primary amines in the presence of 9-borabicyclo[3.3.1]nonane (9-BBN). A wide range of secondary amines and primary amines were successfully methylated under mild conditions. The catalyst sustained over six successive cycles ofN-methylation of secondary amines without compromising its activity, which encouraged us to check its efficacy towards doubleN-methylation of primary amines. Moreover, this method was utilized for the synthesis of two commercially available drug molecules. A detailed mechanistic cycle was proposed by performing a series of control reactions along with the successful characterisation of active catalytic intermediates either by single-crystal X-ray study or by NMR spectroscopic studies in association with DFT calculations.
- Das, Arpan,Maji, Subir,Mandal, Swadhin K.
-
p. 12174 - 12180
(2021/09/28)
-
- Borane-Trimethylamine Complex as a Reducing Agent for Selective Methylation and Formylation of Amines with CO2
-
We report herein that a borane-trimethylamine complex worked as an efficient reducing agent for the selective methylation and formylation of amines with 1 atm CO2 under metal-free conditions. 6-Amino-2-picoline serves as a highly efficient catalyst for the methylation of various secondary amines, whereas in its absence, the formylation of primary and secondary amines was achieved in high yield with high chemoselectivity. Mechanistic studies suggest that the 6-amino-2-picoline-borane catalytic system operates like an intramolecular frustrated Lewis pair to activate CO2.
- Zhang, Yanmeng,Zhang, He,Gao, Ke
-
supporting information
p. 8282 - 8286
(2021/10/25)
-
- Utilization of renewable formic acid from lignocellulosic biomass for the selective hydrogenation and/or N-methylation
-
Lignocellulosic biomass is one of the most abundant renewable sources in nature. Herein, we have developed the utilization of renewable formic acid from lignocellulosic biomass as a hydrogen source and a carbon source for the selective hydrogenation and further N-methylation of various quinolines and the derivatives, various indoles under mild conditions in high efficiencies. N-methylation of various anilines is also developed. Mechanistic studies indicate that the hydrogenation occurs via a transfer hydrogenation pathway.
- Zhou, Chao-Zheng,Zhao, Yu-Rou,Tan, Fang-Fang,Guo, Yan-Jun,Li, Yang
-
p. 4724 - 4728
(2021/09/06)
-
- Photo-induced thiolate catalytic activation of inert Caryl-hetero bonds for radical borylation
-
Substantial effort is currently being devoted to obtaining photoredox catalysts with high redox power. Yet, it remains challenging to apply the currently established methods to the activation of bonds with high bond dissociation energy and to substrates with high reduction potentials. Herein, we introduce a novel photocatalytic strategy for the activation of inert substituted arenes for aryl borylation by using thiolate as a catalyst. This catalytic system exhibits strong reducing ability and engages non-activated Caryl–F, Caryl–X, Caryl–O, Caryl–N, and Caryl–S bonds in productive radical borylation reactions, thus expanding the available aryl radical precursor scope. Despite its high reducing power, the method has a broad substrate scope and good functional-group tolerance. Spectroscopic investigations and control experiments suggest the formation of a charge-transfer complex as the key step to activate the substrates.
- K?nig, Burkhard,Wang, Hua,Wang, Shun
-
supporting information
p. 1653 - 1665
(2021/06/17)
-
- Generation of Aryllithium Reagents from N -Arylpyrroles Using Lithium
-
Treatment of 1-aryl-2,5-diphenylpyrroles with lithium powder in tetrahydrofuran at 0 °C results in the generation of the corresponding aryllithium reagents through reductive C-N bond cleavage.
- Ozaki, Tomoya,Kaga, Atsushi,Saito, Hayate,Yorimitsu, Hideki
-
p. 3019 - 3028
(2021/06/02)
-
- Ruthenium-Catalyzed Isomerization of ortho-Silylanilines to Their para Isomers
-
The catalytic ortho to para transposition of a silyl group in aniline derivatives is described. [RuCl2(p-cymene)]2/BINAP in conjunction with a Cu(OAc)2 additive serves as a potent catalytic system. This method is also applicable to the isomerization of 2-silylpyrrole derivatives to the corresponding 3-silyl isomers.
- Ishiga, Wataru,Ohta, Masaya,Kodama, Takuya,Tobisu, Mamoru
-
supporting information
p. 6714 - 6718
(2021/09/02)
-
- Organic photoredox catalytic α-C(sp3)-H phosphorylation of saturated: Aza -heterocycles
-
A metal-free C(sp3)-H phosphorylation of saturated aza-heterocycles via the merger of organic photoredox and Br?nsted acid catalyses was established under mild conditions. This protocol provided straightforward and economic access to a variety of valuable α-phosphoryl cyclic amines by using commercially available diarylphosphine oxide reagents. In addition, the D-A fluorescent molecule DCQ was used for the first time as a photocatalyst and exhibited an excellent photoredox catalytic efficiency in this transformation. A series of mechanistic experiments and DFT calculations demonstrated that this transformation underwent a sequential visible light photoredox catalytic oxidation/nucleophilic addition process.
- Yi, Ming-Jun,Xiao, Teng-Fei,Li, Wen-Hui,Zhang, Yi-Fan,Yan, Pen-Ji,Zhang, Baoxin,Xu, Peng-Fei,Xu, Guo-Qiang
-
supporting information
p. 13158 - 13161
(2021/12/16)
-
- Iron-catalyzed reductive strecker reaction
-
Strecker reaction is widely applied for the synthesis of amino acids from aldehydes, amines and cyanides. Herein, we report the FeI2-catalyzed reductive Strecker type reaction of formamides instead of aldehydes to produce amino acetonitriles. The challenging capture of carbinolamine intermediates by CN? was achieved via Fe catalysis. This approach afforded better yields than the use of Ir- or Rh-catalysts. The application ability of this methodology is demonstrated by 1) one-pot construction of (13C labeled) complex molecules from CO2 via amino acetonitrile intermediates and 2) convenient production of homologated carboxylic acids from aldehydes.
- Yan, Fachao,Huang, Zijun,Du, Chen-Xia,Bai, Jian-Fei,Li, Yuehui
-
p. 188 - 194
(2021/02/03)
-
- Diethylsilane as a Powerful Reagent in Au Nanoparticle-Catalyzed Reductive Transformations
-
Diethylsilane (Et2SiH2), a simple and readily available dihydrosilane, that exhibits superior reactivity, as compared to monohydrosilanes, in a series of reductive transformations catalyzed by recyclable and reusable Au nanoparticles (1 mol-%) supported on TiO2. It reduces aldehydes or ketones almost instantaneously at ambient conditions. It can be used in a one pot rapid reductive amination procedure, in which premixing of aldehyde and amine is required prior to the addition of the reducing agent and the catalyst, even in a protic solvent. An unprecedented method for the synthesis of N-arylisoindolines is also shown in the reductive amination between o-phthalaldehyde and anilines. In this transformation, it is proposed that the intermediate N,2-diphenylisoindolin-1-imines are reduced stepwise to the isoindolines. Finally, Et2SiH2 readily reduces amides into amines in excellent yields and shorter reaction times relative to previously known analogous nano Au(0)-catalyzed protocols.
- Louka, Anastasia,Kidonakis, Marios,Saridakis, Iakovos,Zantioti-Chatzouda, Elisavet-Maria,Stratakis, Manolis
-
p. 3508 - 3514
(2020/06/02)
-
- Zinc Powder Catalysed Formylation and Urealation of Amines Using CO2 as a C1 Building Block?
-
Transformation of CO2 into valuable organic compounds catalysed by cheap and biocompatible metal catalysts is one of important topics of current organic synthesis and catalysis. Herein, we report the zinc powder catalysed formylation and urealation of amines with CO2 and (EtO)3SiH under solvent free condition. Using 2 molpercent zinc powder as the catalyst, a series of secondary amines, both the aromatic ones and the aliphatic ones, can be formylated into formamides. When primary aromatic amines were used as the substrates, the reactions produce urea derivatives. The electronic and steric effects from the substrates on the formylation and urealation reactions were observed and discussed. The recovery and reusability of zinc powder were investigated, showing the zinc powder can be reused in the formylation reaction without loss of catalytic activity. The analysis on the reactants/products mixture after filtering out the zinc powder showed the zinc concentration in the mixture is low to 1 ppm. The pathways for the formylation and urealation of amines with this catalytic system were also investigated, and related to the different substrates.
- Du, Chongyang,Chen, Yaofeng
-
supporting information
p. 1057 - 1064
(2020/06/30)
-
- ZINC-IMIDAZOLE COMPLEX MIXED CATALYST AND METHOD FOR PRODUCING METHYL N-PHENYL CARBAMATE USING THE SAME
-
Disclosed is a zinc-imidazole complex mixed catalyst. Also disclosed are a method for preparing the zinc-imidazole complex mixed catalyst and a method for producing a methyl N-phenyl carbamate in high yield with high selectivity in the presence of the catalyst. The zinc-imidazole complex mixed catalyst can be reused due to its high reaction stability. In addition, the use of the zinc-imidazole complex mixed catalyst leads to a marked improvement in the production yield of a methyl N-phenyl carbamate with high selectivity.
- -
-
Paragraph 0077-0078; 0089-0090
(2020/03/09)
-
- Facile synthesis of controllable graphene-co-shelled reusable Ni/NiO nanoparticles and their application in the synthesis of amines under mild conditions
-
The primary objective of many researchers in chemical synthesis is the development of recyclable and easily accessible catalysts. These catalysts should preferably be made from Earth-abundant metals and have the ability to be utilised in the synthesis of pharmaceutically important compounds. Amines are classified as privileged compounds, and are used extensively in the fine and bulk chemical industries, as well as in pharmaceutical and materials research. In many laboratories and in industry, transition metal catalysed reductive amination of carbonyl compounds is performed using predominantly ammonia and H2. However, these reactions usually require precious metal-based catalysts or RANEY nickel, and require harsh reaction conditions and yield low selectivity for the desired products. Herein, we describe a simple and environmentally friendly method for the preparation of thin graphene spheres that encapsulate uniform Ni/NiO nanoalloy catalysts (Ni/NiO?C) using nickel citrate as the precursor. The resulting catalysts are stable and reusable and were successfully used for the synthesis of primary, secondary, tertiary, and N-methylamines (more than 62 examples). The reaction couples easily accessible carbonyl compounds (aldehydes and ketones) with ammonia, amines, and H2 under very mild industrially viable and scalable conditions (80 °C and 1 MPa H2 pressure, 4 h), offering cost-effective access to numerous functionalized, structurally diverse linear and branched benzylic, heterocyclic, and aliphatic amines including drugs and steroid derivatives. We have also demonstrated the scale-up of the heterogeneous amination protocol to gram-scale synthesis. Furthermore, the catalyst can be immobilized on a magnetic stirring bar and be conveniently recycled up to five times without any significant loss of catalytic activity and selectivity for the product.
- Cui, Zhibing,Liu, Jianguo,Liu, Qiying,Ma, Longlong,Singh, Thishana,Wang, Chenguang,Wang, Nan,Zhu, Yuting
-
supporting information
p. 7387 - 7397
(2020/11/19)
-
- Catalytic Reductions Without External Hydrogen Gas: Broad Scope Hydrogenations with Tetrahydroxydiboron and a Tertiary Amine
-
Facile reduction of aryl halides with a combination of 5% Pd/C, B2(OH)4, and 4-methylmorpholine is reported. Aryl bromides, iodides, and chlorides were efficiently reduced. Aryl dihalides containing two different halogen atoms underwent selective reduction: I over Br and Cl, and Br over Cl. Beyond these, aryl triflates were efficiently reduced. This combination was broadly general, effectuating reductions of benzylic halides and ethers, alkenes, alkynes, aldehydes, and azides, as well as for N-Cbz deprotection. A cyano group was unaffected, but a nitro group and a ketone underwent reduction to a low extent. When B2(OD)4 was used for aryl halide reduction, a significant amount of deuteriation occurred. However, H atom incorporation competed and increased in slower reactions. 4-Methylmorpholine was identified as a possible source of H atoms in this, but a combination of only 4-methylmorpholine and Pd/C did not result in reduction. Hydrogen gas has been observed to form with this reagent combination. Experiments aimed at understanding the chemistry led to the proposal of a plausible mechanism and to the identification of N,N-bis(methyl-d3)pyridin-4-amine (DMAP-d6) and B2(OD)4 as an effective combination for full aromatic deuteriation. (Figure presented.).
- Korvinson, Kirill A.,Akula, Hari K.,Malinchak, Casina T.,Sebastian, Dellamol,Wei, Wei,Khandaker, Tashrique A.,Andrzejewska, Magdalena R.,Zajc, Barbara,Lakshman, Mahesh K.
-
supporting information
p. 166 - 176
(2020/01/02)
-
- Hydrodebromination of Aromatic Bromides Catalyzed by Unsupported Nanoporous Gold: Heterolytic Cleavage of Hydrogen Molecule
-
Unsupported nanoporous gold (AuNPore) is a highly efficient, practically applicable, and recyclable catalyst for hydrodebromination of aromatic bromides. The AuNPore-catalyzed hydrodebromination of aromatic bromides proceeded smoothly at relatively low hydrogen pressure and temperature to achieve good to excellent yields of the corresponding non-bromine variants. The selective hydrodebromination reaction occurred exclusively in the coexistence of chlorine atom. For the first time, a mechanistic study revealed that the H?H bond splits in a heterolysis manner on the surface of AuNPore to generate Au?H hydride species.
- Bao, Ming,Feng, Xiujuan,Yamamoto, Yoshinori,Zhang, Sheng,Zhao, Yuhui
-
p. 4951 - 4957
(2020/09/09)
-
- Photo-induced dealdehyding method
-
The invention provides a photo-induced dealdehyding method, and belongs to the technical field of organic synthesis. The photo-induced dealdehyding method comprises the following steps that a mixtureof a compound shown in the formula I and a solvent are reacted under an inert gas atmosphere and visible light irradiation, a dealdehyding product is obtained, and no photocatalyst is used in the whole process; wherein the structural formula of the formula I shown in the specification, R is a functional group and is selected from hydrogen, methyl, methoxyl, cyano, chlorine, bromine or fluorine. According to the photo-induced dealdehyding method, in the inert gas atmosphere, the compound shown in the formula (I) can be excited to generate carbon-oxygen bond homogeneous cracking through visiblelight irradiation, then free radical migration and double bond displacement are conducted, finally carbon monoxide is removed, aldehyde group removal is completed, no photocatalyst is needed in the whole process, operation is easy and convenient, and conditions are mild.
- -
-
Paragraph 0048-0053; 0180-0185
(2020/06/16)
-
- Visible-Light-Induced, Base-Promoted Transition-Metal-Free Dehalogenation of Aryl Fluorides, Chlorides, Bromides, and Iodides
-
We report a simple and efficient visible-light-induced transition-metal-free hydrogenation of aryl halides. The combined visible light and base system is used to initiate the desired radical-mediated hydrogenation. A variety of aryl fluorides, chlorides, bromides, and iodides could be reduced to the corresponding (hetero)arenes with excellent yields under mild conditions. Various functional groups and other heterocyclic compounds are tolerated.
- Ding, Ting-Hui,Qu, Jian-Ping,Kang, Yan-Biao
-
supporting information
p. 3084 - 3088
(2020/04/10)
-
- A visible-light-photocatalytic water-splitting strategy for sustainable hydrogenation/deuteration of aryl chlorides
-
Hydrogenation/deuteration of carbon chloride (C?Cl) bonds is of high significance but remains a remarkable challenge in synthetic chemistry, especially using safe and inexpensive hydrogen donors. In this article, a visible-light-photocatalytic watersplitting hydrogenation technology (WSHT) is proposed to in-situ generate active H-species (i.e., Had) for controllable hydrogenation of aryl chlorides instead of using flammable H2. When applying heavy water-splitting systems, we could selectively install deuterium at the C?Cl position of aryl chlorides under mild conditions for the sustainable synthesis of high-valued added deuterated chemicals. Sub-micrometer Pd nanosheets (Pd NSs) decorated crystallined polymeric carbon nitrides (CPCN) is developed as the bifunctional photocatalyst, whereas Pd NSs not only serve as a cocatalyst of CPCN to generate and stabilize H (D)-species but also play a significant role in the sequential activation and hydrogenation/deuteration of C?Cl bonds. This article highlights a photocatalytic-WSHT for controllable hydrogenation/deuteration of low-cost aryl chlorides, providing a promising way for the photosynthesis of high-valued added chemicals instead of the hydrogen evolution.
- Ling, Xiang,Xu, Yangsen,Wu, Shaoping,Liu, Mofan,Yang, Peng,Qiu, Chuntian,Zhang, Guoqiang,Zhou, Hongwei,Su, Chenliang
-
p. 386 - 392
(2020/02/25)
-
- Triazinetriamine-derived porous organic polymer-supported copper nanoparticles (Cu-NPs@TzTa-POP): an efficient catalyst for the synthesis of: N -methylated products via CO2fixation and primary carbamates from alcohols and urea
-
In recent times, carbon dioxide fixation has received much attention for its potential application as an abundant C1 source and a range of important fine chemicals can be manufactured via this fixation. Here, a copper nanoparticle-decorated porous organic polymer-based (Cu-NPs@TzTa-POP) material was prepared by a simple in situ process. The catalyst was characterized by various techniques such as UV-vis spectra, FTIR spectra, HR-TEM, PXRD, N2 adsorption-desorption, TG-DTA, XPS, and AAS analysis. The synthesized heterogeneous catalyst showed excellent activity in an atmospheric carbon dioxide fixation reaction to produce N-methylated products from aromatic/heterocyclic amines in the presence of polymethyl-hydrosiloxane (PMHS) as the reducing agent at 80 °C within 12 h of the reaction. Through this catalytic N-methylation reaction, we obtained 98% yield of the product with turnover frequency ranging from 18 to 42 h-1. The catalyst is also very stable for the formation of primary carbamates from alcohols using the eco-friendly carbonylating agent, urea. Diverse alcohols (such as benzylic alcohols, phenols, heterocyclic alcohols, as well as aliphatic alcohols) showed much acceptance to this catalytic reaction and produced moderate to excellent yields of the respective carbamate products under ambient reaction conditions. Moreover, Cu-NPs@TzTa-POP is effortlessly recyclable and reusable without the extensive loss of active copper metal centres for many catalytic rounds (up to six catalytic rounds were examined).
- Haque, Najirul,Biswas, Surajit,Basu, Priyanka,Haque Biswas, Imdadul,Khatun, Resmin,Khan, Aslam,Islam, Sk Manirul
-
supporting information
p. 15446 - 15458
(2020/10/22)
-
- Selective: N-formylation/N-methylation of amines and N-formylation of amides and carbamates with carbon dioxide and hydrosilanes: Promotion of the basic counter anions of the zinc catalyst
-
A catalyst composed of commercially available Zn(OAc)2 and 1,10-phenanthroline (phen) was effective in the N-formylation/N-methylation of amines using CO2 as the C1 source in the presence of hydrosilanes. An equimolar reaction of N-methylaniline with PhSiH3 under a CO2 atmosphere yielded the N-formylation product in 92% yield at 25 °C. Scale-up of the reaction using 10 mmol substrate was also successful in affording the desired product in 83% yield (1.1 g). This catalyst exhibits a high thermal stability and a turnover number (TON) of 385000 at 150 °C. In addition, the reaction of N-methylaniline in the presence of excess Ph2SiH2 produced N,N-dimethylaniline. Furthermore, our catalytic protocol was developed for the N-formylation of amides and carbamates, which have smaller pKa values and lower reactivities than the corresponding amines. The present Zn(OAc)2/phen catalyst was found to show versatility in the conversion of CO2 and amines into several functionalized organic chemicals under mild conditions. We propose that the basic counter anion (i.e., the acetate) of the catalyst activates both the Si-H and N-H bonds.
- Zhang, Qiao,Lin, Xiao-Tao,Fukaya, Norihisa,Fujitani, Tadahiro,Sato, Kazuhiko,Choi, Jun-Chul
-
supporting information
p. 8414 - 8422
(2020/12/29)
-
- Catalyst-free selective: N -formylation and N -methylation of amines using CO2 as a sustainable C1 source
-
We herein describe catalyst-free selective N-formylation and N-methylation of amines using CO2 as a sustainable C1 source. By tuning the reaction solvent and temperature, the selective synthesis of formamides and methylamines is achieved in good to excellent yields using sodium borohydride (NaBH4) as a sustainable reductant.
- Zou, Qizhuang,Long, Guangcai,Zhao, Tianxiang,Hu, Xingbang
-
supporting information
p. 1134 - 1138
(2020/03/11)
-
- Alkyl-substituted ethyl acetate-based guanidine ionic liquid as well as preparation and application thereof
-
The invention discloses alkyl-substituted ethyl acetate-based guanidine ionic liquid as well as preparation and application thereof, which are characterized in that tetramethylguanidine and 2-bromo ester are ionized to obtain alkyl-substituted ethyl acetate-based guanidine ionic liquid, and the alkyl-substituted ethyl acetate-based guanidine ionic liquid is applied as a catalyst to formylation and methylation reactions of carbon dioxide, N-methylaniline and derivatives of the N-methylaniline to selectively generate N-methylformylaniline or N, N-dimethylaniline and derivatives thereof. Compared with the prior art, the alkyl-substituted ethyl acetate-based guanidine ionic liquid has the advantages of good catalytic performance, mild reaction conditions, simple post-treatment, simple synthesis, low cost, greenness and high efficiency, avoids the use of a large amount of organic solvents when being used as a solvent and a catalyst at the same time, and has important meanings in the research of medicinal chemistry and medical intermediate compounds.
- -
-
Paragraph 0046-0049
(2020/07/21)
-
- Engineering Porphyrin Metal-Organic Framework Composites as Multifunctional Platforms for CO2Adsorption and Activation
-
As an effective solution toward the establishment of a sustainable society, the reductive transformation of CO2 into value-added products is certainly important and imperative. Herein, we report a porphyrin metal-organic framework composite Au@Ir-PCN-222, which is obtained through the in situ formation of Au nanoparticles in the coordination interspaces of Ir-PCN-222. Catalytic results show that Au@Ir-PCN-222 is highly efficient for CO2 reduction and aminolysis, giving rise to formamides in high yields and selectivities under room temperature and atmospheric pressure. Mechanistic studies disclose that the high efficiency of Au@Ir-PCN-222 is due to the synergistic catalysis of Au NPs and Ir-PCN-222, in which Au NPs can adsorb CO2 molecules on their surfaces and then increase the CO2 concentration in the cavities of the framework, and at the same time, Au NPs transfer electrons to Ir-porphyrin units and therefore increase the interactions with CO2 molecules.
- Liu, Jiewei,Fan, Yan-Zhong,Zhang, Kun,Zhang, Li,Su, Cheng-Yong
-
p. 14548 - 14556
(2020/10/13)
-
- N-Heterocyclic Carbene-Stabilized Germa-acylium Ion: Reactivity and Utility in Catalytic CO2Functionalizations
-
The first acceptor-free heavier germanium analogue of an acylium ion, [RGe(O)(NHC)2]X (R = MesTer = 2,6-(2,4,6-Me3C6H2)2C6H3; NHC = IMe4 = 1,3,4,5-tetramethylimidazol-2-ylidene; X = (Cl or BArF = {(3,5-(CF3)2C6H5)4B}), was isolated by reacting [RGe(NHC)2]X with N2O. Conversion of the germa-acylium ion to the first solely donor-stabilized germanium ester [(NHC)RGe(O)(OSiPh3)] and corresponding heavier analogues ([RGe(S)(NHC)2]X and [RGe(Se)(NHC)2]X) demonstrated its classical acylium-like behavior. The polarized terminal GeO bond in the germa-acylium ion was utilized to activate CO2 and silane, with the former found to be an example of reversible activation of CO2, thus mimicking the behavior of transition metal oxides. Furthermore, its transition-metal-like nature is demonstrated as it was found to be an active catalyst in both CO2 hydrosilylation and reductive N-functionalization of amines using CO2 as the C1 source. Mechanistic studies were undertaken both experimentally and computationally, which revealed that the reaction proceeds via an N-heterocyclic carbene (NHC) siloxygermylene [(NHC)RGe(OSiHPh2)].
- Sarkar, Debotra,Weetman, Catherine,Dutta, Sayan,Schubert, Emeric,Jandl, Christian,Koley, Debasis,Inoue, Shigeyoshi
-
supporting information
p. 15403 - 15411
(2020/10/20)
-
- Catalyst-free photodecarbonylation ofortho-amino benzaldehyde
-
It is almost a consensus that decarbonylation of the aldehyde group (-CHO) needs to not only be mediated by transition metal catalysts, but also requires severe reaction conditions (high temperature and long reaction time). In this work, inspired by the “conformational-selectivity-based” design strategy, we broke this consensus and discovered a catalyst-free photodecarbonylation of the aldehyde group. It revealed that decarbonylation can be easily achieved with visible light irradiation by introducing a tertiary amine into theortho-position of the aldehyde group. A diverse array of tertiary amines is tolerated by our photodecarbonylation under mild conditions. Furthermore, the (QM) computations of the mechanism and the experiments on well-designed special substrates revealed that our photodecarbonylation depends on the conformational specificity of the aldehyde group and tertiary amine, and occurs through an unusual [1,4]-H shift and a subsequent [1,3]-H shift.
- Li, Lamei,Wang, Songping,Wei, Wentao,Yan, Ming,Zhou, Jingwei
-
supporting information
p. 3421 - 3426
(2020/06/25)
-
- Synthesis of unsymmetrically substituted triarylaminesviaacceptorless dehydrogenative aromatization using a Pd/C andp-toluenesulfonic acid hybrid relay catalyst
-
An efficient and convenient procedure for synthesizing triarylamines based on a dehydrogenative aromatization strategy has been developed. A hybrid relay catalyst comprising carbon-supported Pd (Pd/C) andp-toluenesulfonic acid (TsOH) was found to be effective for synthesizing a variety of triarylamines bearing different aryl groups starting from arylamines (diarylamines or anilines), using cyclohexanones as the arylation sources under acceptorless conditions with the release of gaseous H2. The proposed reaction comprises the following relay steps: condensation of arylamines and cyclohexanones to produce imines or enamines, dehydrogenative aromatization of the imines or enamines over Pd nanoparticles (NPs), and elimination of H2from the Pd NPs. In this study, an interesting finding was obtained indicating that TsOH may promote the dehydrogenation.
- Jin, Xiongjie,Koizumi, Yu,Mizuno, Noritaka,Nozaki, Kyoko,Takayama, Satoshi,Yamaguchi, Kazuya,Yatabe, Takafumi
-
p. 4074 - 4084
(2020/05/25)
-
- Mild catalytic deoxygenation of amides promoted by thorium metallocene
-
The organoactinide-catalyzed (Cp*2ThMe2) hydroborated reduction of a wide range of tertiary, secondary, and primary amides to the corresponding amines/amine-borane adductsviadeoxygenation of the amides is reported herein. The catalytic reactions proceed under mild conditions with low catalyst loading and pinacolborane (HBpin) concentration in a selective fashion. Cp*2ThMe2is capable of efficiently catalysing the gram-scale reaction without a drop in efficiency. The amine-borane adducts are successfully converted into free amine products in high conversions, which increases the usefulness of this catalytic system. A plausible mechanism is proposed based on detailed kinetics, stoichiometric, and deuterium labeling studies.
- Eisen, Moris S.,Saha, Sayantani
-
supporting information
p. 12835 - 12841
(2020/10/05)
-
